The air at the ground is at a higher pressure than air higher up; this is because the air at the ground is compressed by the weight of all the air above it. Air weighs quite a lot: A square column of air one meter across weighs ten tonnes! The air pressure decreases steadily as you go up, since there's less air pressing down from above, until you reach zero pressure, which is outer space.
If you've ever opened a container of compressed gas, like a bottle of carbon dioxide or nitrogen, you'll notice that the air coming out of it is very cold. (Even a bottle of soda does this a little; it's the cold that makes it "steam" briefly when opened.) Reducing the pressure makes most gases colder.
In what follows, I'll talk a lot about "air parcels". You should imagine a "chunk" of air, identical to the air around it, but identified by drawing an imaginary boundary around it, or by marking each of the molecules in it with a little tattoo.
Now, the air in the lower atmosphere (the "troposphere") is constantly mixed by convection, which results from sunlight heating the ground. So air parcels are being constantly lifted from the ground to high altitude and back again. As a chunk of air rises, its pressure decreases, and so its temperature drops. Descending parcels are warmed as they're compressed. This is what makes the air cooler higher up: the process is called adiabatic expansion/compression.
But why do gases cool when they're compressed? I'll give a verbal and a mathematical explanation. Imagine a parcel rising from the ground high into the atmosphere without gaining any net energy. As it rises, it is gaining gravitational potential energy. This energy must come from somewhere: the only source of energy is the internal thermal energy of the molecules in the parcel -- the energy in the shaking and jiggling of the molecules. If the molecules shake and jiggle less, it means they must have a lower temperature.
The mathemtical explanation: you may have heard of the ideal gas law:
PV = nRT (1)which says that gas pressure (P) times volume (V) is proportional to the temperature (T). (n is the number of moles of gas molecules in the parcel, and R is a fundamental constant; both remain the same in this problem). So we see that when P goes down (on top of the mountain), T also goes down. But wait! The volume V of the gas goes up at the same time, which would increase the temperature! Which of P and V wins?
To find the answer, we need the "adiabatic expansion" equation, which says that if no energy is gained or lost by an air parcel,
P Vgamma = constant = P0 V0gamma (2)where P0 is the pressure and V0 is the volume before we expanded or compressed the gas. Putting equation 1 into equation 2, we can eliminate the volume V:
P/P0 = (V/V0)(-gamma) V = V0 (P/P0)(-1/gamma) PV = P V0(P/P0)(-1/gamma) (n R) P(1-1/gamma) = ----- P0(-1/gamma) T V0Since n, R, P0, and V0 are all constants, this is an equation relating pressure P to temperature T for a parcel. As long as (1-1/gamma) > 0, T will decrease whenever P decreases (as we go up in the atmosphere). gamma = 1.4 for air, giving (1-1/gamma) = .28 > 0. Therefore, the atmosphere gets colder as you go up and pressure decreases.
Why does the ideal gas law hold? Where does the adiabatic expansion law come from? Why is gamma = 1.4 for air? These are much harder questions, dealt with in college thermodynamics courses, and beyond the scope of this question.
The change in temperature when heat flows into an object is an increase. This increase in temperature occurs as the object absorbs the heat energy and its particles gain kinetic energy, causing them to move faster and the object's temperature to rise.
Change in temperature is what cause the Mercury to expand up (hotter) or shrink down (colder).
The change in temperature is 25 degrees. This is calculated by subtracting the initial temperature (-10) from the final temperature (15).
The air thermoscope works by using the expansion and contraction of air due to changes in temperature. As the air warms up, it expands and pushes a liquid (usually colored alcohol) up a narrow tube. This change in liquid level indicates the temperature change.
The temperature generally decreases as you climb higher up a mountain due to lower air pressure and thinner atmosphere. This change in temperature with altitude is known as the lapse rate, and it results in colder temperatures at higher elevations.
Morton Tavel has written: 'Contemporary Physics and the Limits of Knowledge'
No, my temperature does not change as I am a computer program.
yes they do
Hans-Christoph von Tavel has written: 'Nationale bildthemen'
If water is warmed up, then that means that its temperature does change.
it goes up in 3's
Ronald Tavel was born on May 17, 1936, in Brooklyn, New York City, New York, USA.
Provence, France
having a rave in tavel and tourism ;)
It depends, but usually extreme temperature speeds it up! Good Luck!
Ronald Tavel died on March 23, 2009, in aboard a flight from Berlin, Germany to Bangkok, Thailand of heart attack.
A salamander is a cold blooded animal. So it simply follows the temperature change. Temperature goes down, its body temp goes down, Temp goes up its body temp goes up